| /* |
| * Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You under the Apache License, Version 2.0 |
| * (the "License"); you may not use this file except in compliance with |
| * the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.xmlgraphics.image.codec.util; |
| |
| import java.io.IOException; |
| import java.io.InputStream; |
| |
| /** |
| * A subclass of <code>SeekableStream</code> that may be used |
| * to wrap a regular <code>InputStream</code> efficiently. |
| * Seeking backwards is not supported. |
| * |
| */ |
| public class ForwardSeekableStream extends SeekableStream { |
| |
| /** The source <code>InputStream</code>. */ |
| private InputStream src; |
| |
| /** The current position. */ |
| long pointer = 0L; |
| |
| /** The marked position. */ |
| long markPos = -1L; |
| |
| /** |
| * Constructs a <code>InputStreamForwardSeekableStream</code> from a |
| * regular <code>InputStream</code>. |
| */ |
| public ForwardSeekableStream(InputStream src) { |
| this.src = src; |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final int read() throws IOException { |
| int result = src.read(); |
| if (result != -1) { |
| ++pointer; |
| } |
| return result; |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final int read(byte[] b, int off, int len) throws IOException { |
| int result = src.read(b, off, len); |
| if (result != -1) { |
| pointer += result; |
| } |
| return result; |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final long skip(long n) throws IOException { |
| long skipped = src.skip(n); |
| pointer += skipped; |
| return skipped; |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final int available() throws IOException { |
| return src.available(); |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final void close() throws IOException { |
| src.close(); |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final synchronized void mark(int readLimit) { |
| markPos = pointer; |
| src.mark(readLimit); |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public final synchronized void reset() throws IOException { |
| if (markPos != -1) { |
| pointer = markPos; |
| } |
| src.reset(); |
| } |
| |
| /** Forwards the request to the real <code>InputStream</code>. */ |
| public boolean markSupported() { |
| return src.markSupported(); |
| } |
| |
| /** Returns <code>false</code> since seking backwards is not supported. */ |
| public final boolean canSeekBackwards() { |
| return false; |
| } |
| |
| /** Returns the current position in the stream (bytes read). */ |
| public final long getFilePointer() { |
| return pointer; |
| } |
| |
| /** |
| * Seeks forward to the given position in the stream. |
| * If <code>pos</code> is smaller than the current position |
| * as returned by <code>getFilePointer()</code>, nothing |
| * happens. |
| */ |
| public final void seek(long pos) throws IOException { |
| while (pos - pointer > 0) { |
| pointer += src.skip(pos - pointer); |
| } |
| } |
| } |